Percussive tool blowing device



y 7, 936. w. A. SMITH, JR ,046,659

. v ZPERCUSSIVE TOOL BLOWING DEVICE Filed May 10, 1934 INVENTOR BY m ATTORNEY i atentecl July 7, I936 PERCUSSIVE TOOL DEVICE William A. Smith, Jr., Not-til Arlington, N. J., assignor to Worthington Pump and Machinery Corporation, New York, I], a corporation of Virginia.

Application May 10, 1934,, Serial No. 224,889 2 Claims. (Cr er-10 'I'hisinvention relates to percussive. tools, such as'rock drills of the hammer piston type, and more particularly to a blowing device-for blowing or cleansing the drill hole;

An object of the present invention is to provide in a pressure operated hammer pistontool, means wherebypressure fluid used to operate the tool may be selectively admitted .to the front end of the tool for passage through the hollow drill steel for cleansing the drill hole, and also to provide means for balancing the hammer piston during the blowing operation.

' With these and other objects in view as may appear from the accompanying specificatiom'the invention consists, of various features of construction and combination of. parts, which will be first described in connection with the accom' panying drawing showing a longitudinal section through a percussive tool embodying the blowing device, and the features forming the invention will be specifically pointed out in the claims.

Referring more particularly to the drawing, the improved rock drill comprises a cylinder I in which the hammer piston 2 reciprocates. The hammer piston 2 has an extension 3 formed thereon which strikes the drill bar or working tool 4 for operating the tool. The extension 3 is fluted as shown at 5, and it is customary in percussive tools of this type to permit rotation of the working tool 4 through the medium or the chuck mechanism 6, by rotation of the piston 3 through the medium of the rifle bar rotating mechanism 1. The rifle bar rotating mechanism 1 is well known in the art and since it forms no part of the present invention it will not be specifically described herein.

The hammer piston 2 is reciprocated in the cylinder l by pressure fluid such as compressed air and the delivery of the pressure fluid while the distribution of the pressure, to cause proper reciprocation of the piston 2, is controlled by means of the distributing valve 9.

The cylinder 2 has an exhaust port 10 therein which opens to atmosphere and which is controlled by the piston 2. The exhaust port l0 permits the exhausting of the air or pressure fluid from the ends of the cylinder I at the proper times during the operation of the tool, as is customary in percussive tools of the hammer piston type. The cylinder 1 has a front cylinder washer H mounted therein, the lower end of which receives the section l2 of the chuck mechanism 6.

At times, it is desirable to clean the drill hole 'being drilled by the drill bar 4, and to provide for such cleaning a blowing passage [4 is formed in the cylinder 1. The blowing passage M has communication through a branch passage l5 with thethrottle. valve 8 so that when the throttle valve .8 is in the position shown in the drawing, 5 the liveor unused pressure fluid will be cut ofi from delivery to the distributing valve 9 and directed upwardly through the blowing passage 14. From the blowing passage M the pressure fluid passes, through the branch passage it into 10 the annular channel ll. As shown in the drawings, the annular channel I! is formed part in the front cylinder washer H and part in the section [2 of the chuck mechanism. Transverse port or ports [8 communicate with the annular channel I1 and open into the chamber l9 formed in the chuck; mechanism outwardly of the end of the piston extension 5, so that the blowing air will pass through the blowing passage I4, branch passage i6 and into the annular channel I! from which some of it will pass through the port or ports I8 into the chamber I9. From the chamber [9 the majority of the blowing air will pass out through the bore 20, in the drill bar 4 or other working tool for the purpose of blowing out and cleansing the drill hole.

Some of the blowing air will pass upwardly through the flutes 5 in the piston extension 3 into the cylinder I forwardly of the piston 2.

For the purpose of preventing movement of the piston during the blowing operation, that is, for the purpose of balancing the piston against the pressure of the blowing air which passes into the cylinder through the flutes 5, a return blowing passage 2| is formed in the cylinder I. The return blowing passage 2| has communication with the annular channel I! through a branch passage 23 and its upper end opens out through a port 24 into the cylinder I on the opposite side of the exhaust port II] from the annular channel H and consequently on the opposite side of the exhaust port from the portion of the cylinder into which the blowing air passes through the flutes. Theport 24 is of such area, together with passages 2! and 23, that the blowing air delivered to the rear end of the cylinder on the opposite side of the piston 2 from the portion of the cylinder into which the blowing air enters, will act to balance the piston 2 and hold it against movement during the blowing operation.

When pressure fluid is being delivered to the rear end of the cylinder I and the piston 2 is moving forwardly, as the piston uncovers the port 24 a puff of blowing air will pass through the port 24, down through the passages 2| and 23 through 55 7 hole is shallow but when the hole becomes deep it will only be sufficient to temporarily cleanse the cuttings from about the bit. 7

Summing up generically; when the throttle valve 8 is moved to deliver air to the blowing pas: sage for the purpose of blowing or cleansing the hole, this air or pressure fluid will pass through the blowing passage l4 into the annular channel H from which the major part of the air under pressure will pass into the chamber l9 and out through the bore 20 in the working tool 4, thoroughly blowing or cleansing the drill hole. Part of the air will leak through the flutes 5 into the forward end of the cylinder forwardly of the piston 2. To counterbalance this leakage of blowingiair, a certain amount of the blowingair will passthrough the return blowing passage 2| and port 2e into the cylinder on the. opposite side .of the piston, thus substantially equalizing the pressure on both sides of the piston and holding it against movement during the blowing operation. Itwillbe understood that the invention is not to be limited to the specific construction or arrangement of parts shown but that they may be widely modified within the invention defined by the claims. A r What is claimed is: I V

1 1. In a percussive tool, the combination, of a cylinder having a main exhaust port, a piston in 1 'the'cylinder controlling the exhaust port, athrottle valve for controlling the delivery of operating pressure fluid to the drill, a chuck structure in the forward end of the cylinder, an extension on the piston having flutes therein, a working implement acted upon by said'hammer piston and having a bore, a blower passage leading from said throttle valve to said chuck structure and. controlled by said throttle valve for supplying pressure fluid to said working implement and through said flutes 'to the cylinder forwardly of the ex haust port, and a return blower passagein said a cylinder opening into the cylinder rearwardly of j said exhaust port for conveying pressure fluid to y the'cylinder for balancing said piston during the blowing of the drill hole, said return passage opening into said cylinder at a point whereby the cylinder will be cut oil from exhausting communication'with atmosphere during the return of blowing air thereto. 7

2. Inia percussive tool, the combination, of a cylinderhaving a, main exhaust port, a piston in the cylinder controlling said exhaust port, a chuck structure in the forward end of the cylinder, aworking implement acted upon by said hammer piston. and having a bore therein, said cylinder provided with a return blower passage 

